This control includes an inertial pendulum having a mass on a lower end of a pendulum shaft having an upper end pivotably connected through a first pivot to a link acting on the headlamp. Brackets on the body support a V-shaped chassis having upper ends of the arms of the V mounted on the brackets to pivot about coaxial second pivots defining a primary axis transversely of the body. Intermediate its ends the shaft is pivotably mounted by a third pivot on lower ends of the arms of the V. This third pivot provides a secondary axis transversely of the body. The chassis acts on a first shock absorber whilst the pendulum shaft acts on a weaker second shock absorber. With the vehicle standing on the level, the first pivot is coaxial with the primary axis. During acceleration or deceleration the first shock absorber holds the chassis stationary whilst the pendulum swings about the secondary axis, against the action of the second shock absorber, and moves the link which pivots the headlamp relative to the body. Such lamp movement is undesirable when the vehicle is merely travelling up or down hill in which circumstance the pendulum and chassis overcome the shock absorbers and swing together, into a vertical position, about the primary axis thus transmitting no motion to the link.
This invention relates to a corrective device for the orientation of a headlight of motor vechicle wherein the headlight is mounted to rotate about a fixed horizontal axis on a suspended body of the vehicle.
It particularly concerns a dynamic corrective device mounted on a motor vehicle in order to modify the orientation of a headlight by compensating for the effect of dynamic changes in position of the suspended part or body of the vehicle in relation to a non-suspended part for example the road wheels. In most modern vehicles, when the vehicle is in motion, the suspended body is subject to movements relative to the non-suspended part. In particular, when the vehicle is accelerating the front section of the vehicle rises, whilst when braking or decelerating it is lowered in relation to the wheels.
In such circumstances the headlights mounted on the suspended body become inefficient, in that they may shine too high (due to raising of a front section of the body) or they are directed too low (due to lowering of the same front section).
To correct such inconveniences it has already been proposed to mount the headlights in such a way that they swing around an axis which is horizontal and transverse to the body, and to make their position vary around the axis in accordance with the line of pitch of the suspended body of the vehicle. The known corrective device comprises an inertial mass which is suspended in relation to the body, and movements of the mass relative to the body are transmitted to the headlight. The inertial mass acts like an inertial pendulum which moves away from the vertical during acceleration and deceleration of the vehicle and transmits to the headlight a compensatory change in orientation. Examples of this are described in United Kingdom Pat. No. 1 489 924 and U.S. Pat. No. 1,785,332.
Devices of this kind give satisfaction in that they provide compensation for the effects of acceleration and deceleration on the orientation of the headlight's beam.
However, they have one major inconvenience. On rising and descending gradients the inertial pendulum acts like a gravitational pendulum and its position in relation to the body of the vehicle is thus modified. This results in a modification of the positioning of the headlights in relation to the body of the vehicle, which becomes a permanent maladjustment in the orientation of the headlights. This maladjustment is proportional to the gradient of the road on which the vehicle is travelling.
The present invention proposes to provide a corrective device capable of being constructed to overcome or at least mitigate this problem.
According to the invention there is provided a corrective device for the orientation of a headlight on a motor vehicle wherein the headlight is mounted to rotate about a fixed horizontal axis on a suspended body of the vehicle, comprising an inertial pendulum movable in relation to the body and joined to a point on the headlight, said point not being situated on said axis of rotation, a chassis suspended to pivot relatively to the body about a primary axis extending transversely of the body, first shock absorbing means fitted to the chassis for limiting swinging of the chassis in relation to the body, the inertial pendulum being suspended from the chassis and being pivotable about a secondary axis extending transversely of the body, second shock absorbing means fitted to the pendulum for limiting the movement of the pendulum in relation to the body, and said pendulum being joined to the headlight by the intermediary of a mechanical control link joined to the pendulum at the level of said primary axis.
When the vehicle travels along a sloping surface, the device comprising the chassis and the inertial pendulum comes to occupy a stable position in the vertical plane passing through the primary axis, and a pivot connection between the pendulum and the control link remains coincident with the primary axis, so that the control of the headlight is not influenced by the gradient. However, the orientation of the headlight is varied during acceleration and deceleration of the vehicle.
In a preferred embodiment the chassis has the form of a stirrup part with two branches apertured at their ends so that the holes at corresponding ends of the branches face each other, the holes at one set of corresponding ends allow a mounting of the chassis so that it is rotatable on two pivots forming the primary axis, whilst a shaft fits into the holes which coincide at the other ends of the branches and forms the secondary axis.
Preferably the pendulum comprises an inertial mass mounted on a second shaft having a bearing receiving the first mentioned shaft, the second shaft has an aperture receiving a pivot of a third shaft, the mechanical control link comprises said third shaft, and the distance between the bearing and said aperture corresponds to that between the secondary axis and the primary axis.
So that the corrective device is sufficiently sensitive, the first shock absorbing means attached to the chassis has greater damping characteristics than those of the second shock absorbing means attached to the pendulum, so that the pendulum can move in relation to the chassis during acceleration and/or deceleration of the vehicle.
Preferably a means of spacing should be provided on the control link in order to allow an initial adjustment by the driver of the headlight in relation to the body by varying the distance between the points where the mechanical link joins the headlight and the pendulum. In another advantageous variation the means of spacing is mounted on the body and allows a controlled displacement of the primary axis, which leads in corresponding fashion to a swing of the headlight in relation to the body.
Preferably the means of spacing comprises a hydro-mechanical transducer.